Apparatus for handling and burning coal



Dec'. 10, 1940. H. c. CARTER 2,224,760

APPARATUSA FOR HANDLING AND BURNING COAL Filed Dec. 21, 1937 2 sheets-sheet 1 INVENTOR. H C .CARTER Dec. 10, 1940. H. c. CARTER APPARATUS FON HANDLING AND BURNING COAL Filed Dec. 21, 19:57

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Patented Dec. 10, 1940 PATENT OFFICE l 2,224,760 APPARATUS' ronfriggme AND BUnNiNG Haskell Carter, Portland, Greg. Application December 21, 1937, Serial No. y130,954

l Y l Claim.

This invention relates -generally tothe burning of solid fuel. and particularly to a method of and apparatus for' handling and burning fuel.

The main object of this invention istoycon- '5 struct an apparatus for conveying lump coal into a combustion chamber from a remote Y point of storage and to d o so satisfactorily when the coal sizes vary from lumps of three inches in length down to dust vor whether the moisture content ofthe coal is extremely high or a considerable amount, of dirt'is included with the fuel. i

The second object is to develop a method for conveying fuelxpn'eumatically in which the conveying air is heated for the purpose of drying the fuel and preventing packing at the bends in the conveying pipe.

The third object is to utilize gaseous products of combustion as a conveying medium and thereby utilize their inert properties in order to provide a suicient conveying medium without providing an excess of combustion air.

The fourth object is to provide a means for controlling the* temperature of the conveying air.

These and other objects are accomplished in the manner set forth in the following specification as illustrated in the accompanying drawings, in which:

Fig. 1 is a perspective view showing the furnace broken away in section to disclose the grates and the conveying air line.

Fig. 2 is a fragmentary side elevation showing the fan drive and control dampers.

Fig. 3 is a fragmentary section taken along the line 3-3 in Fig. 2.

Fig. 4 is a fragmentary section showing the relation between the coal storage bin, the coal conveying tube and the coal conveying drive.

Fig. 5 is a fragmentary section taken along the line 5-5 in Fig. 4.

40 Similar numerals refer to throughout the several views.

Referring in detail to the drawings, there is shown a set of grates I0 around which are disposed the furnace front I I, the sides I 2 and the bridge wall I3. The space above the grates I l) constitutes a combustion chamber and the space below the grates I3 constitutes an ash pit I4 from which ashes may be rwithdrawn through the ash pit door I5. Secondary air is supplied to the ash pit I4 through the duct I5 by means of a fan I1 which is driven by a motor I8.

Fuel is stored in .a bin IS through which extends a worm 20 which ls driven by a motor 2i through a reduction gearing contained in the transmission casing 22. The worm 20 extends similar parts into the coal conveying tube 23. It is desirable to provide a clean-out gate 24 at the junction of the tube 23 and the bin I9.

The tube 23 communicates with a transfer housing 25 within whose circular opening 26 is mounted the paddle 2l which is secured on the end of the worm 2D. The housing 25 has formed around lthe major portion of the opening 26 a wall 28. The wall 29 forms a part of the housing 25 and extends around the side of the opening 25 which is not enclosed by the wall 23.

` An outlet pipe 35 communicates through the top 3I with the space 32 of the housing-25. The

housing 25 is connected by means of the squarey sprocket wheel 43. In the pipe 36 is also placed V a thermostatic element 44 on whose shaft 45 is mounted a sprocket wheel 45, A chain 41 passes around the sprocket wheels 43, 43 and 46;

Under the control of the element 44, the dampers 38 and 4I are operated in unison, that is, as the temperature of the air entering the fan 34 `exceeds a predetermined value, then the damper 38 is moved toward an open position while the damper 4I ismoved toward a closed position. l y

The pipe 35 connects with the horizontal warm air duct 48 which extends through the furnace front II and the bridge wall I3 and communicates with the space 49 behind the bridge wall I3 from whence heated inert gases may be withdrawn and ydelivered by the fan 34 to the duct 33. The vertical outlet pipe 30 is provided with an elbow 50 at its upper end and is joined by suitable piping 5I and elbows 52 to the nozzle 53.

The operation of this form of the device is as follows:

When the motor 2I is operated, it causes the worm 20 to rotate and to drop fuel over the end 540i the wall 23 into the space 32. While this is taking place, the fan 34 is delivering the heated gases from the space 43 behind the bridge wall I3 and driving the heated gas through the space 32 carrying with the heated gas the coal which is falling therein and carrying the coal upwardly through the pipe 33 past the Various elbows 5i) and 52 and the piping 5I and thence through the nozzle 53 onto the grates Iii.l As the temperature of the space 48 varies, so will the temperature and density of the coal conveying air vary and as the density of the conveying air changes, it will vary its ability to carry fuel. If, for eX- ample, the density of the conveying gases and air decreases, the weight per minute of this medium delivered by the fan.34 naturally decreases.

While it is necessary to propel the conveying medium at a relatively high speed in order to carry the larger chunks of fuel, it is also desirable to maintain a relatively high temperature in order that the fuel may be dried to a point at which it will not adhere to the walls of the conveying conduit and especially at the elbows thereof. This is especially true of the elbow 50 since the velocity of the conveying element must be suiciently great to elevate the coal to a point past the elbow 50 causing it to strike this elbow with considerable force and if the coal is wet and unclean, it will adhere to the elbow 50 and ultimately stop the ow of fuel through the piping 5|.

If the temperature of the conveying gases rises, the thermostatic element 44, which is responsive to the temperature of the mixture of gas and air which enters the fan 34, will cause the damper 38 to open and the damper 4| to close in proportion to the amount of temperature rise thereby increasing the proportion of cold air and decreasing the proportion of the heated gas being used for conveying purposes.

Another advantage arising from the use of balanced dampers at the fan inlet is in the stabilizing of the load on the fan. 'Ihis is due to the fact that if the air is cold, the density of air handled is greater and the load on the fan increases correspondingly. Therefore, by maintaining a relatively ilxed temperature for the gas and air handled by the fan 34, the load on the motor 35 is rendered more uniform.

Obviously, other means could be provided for regulating the temperature and amount of air flow, the type herein presented being merely representative and being used for the purpose of illustrating the invention itself.

Attention is called to the co-pending Patent No. 2,158,673, May 16, 1939, to Carter, et al. over which this device is an improvement.

I claim:

In a stoking apparatus of the class described, the combination of a pneumatic coal delivery conduit having a nozzle at its discharge end whereby coal may be spread over a grate area, a fan for drawing products of combustion from a furnace and delivering the same as heated inert gas to said coal delivery conduit, an air inlet to said fan, dampers for controlling the flow of said air and inert gas and a thermostatic device connected to said dampers to operate the same simultaneously whereby the proportion of inert gas delivered by said fan will be decreased as the temperature of the fuel conveying medium rises above a predetermined maximum and the proportion of air delivered to said fan will be decreased when the temperature of the conveying gases falls below a predetermined minimum.

HASKELI.: C. CARTER. 

